Process for preparation of flannel fabrics from synthetic fibers



Feb. 7, 1967 w. E. DAVIS ETAL 3,302,265

PROCESS FOR PREPARATION OF FLANNEL FABRICS FROM SYNTHETIC FlBERS Filed April 21, 1964 United States Patent C) 3,302,265 PROCESS FOR PREPARATION F FLANNEL FABRICS FROM SYNTHETIC FIBERS Warren E. Davis, Arden, and Edward A. McAbee, Wilmington, Del., assignors to E. I. du Pont de Nemours aud Company, Wilmington, Del., a corporation of Delaware Filed Apr. 21, 1964, Ser. No. 361,546 2 Claims. (Cl. 28-76) This invention relates to fabrics and in particular to flannel fabrics made entirely of man-made fibers.

Flannel fabric is a basic type of textile fabric and finds wide application in apparel, home furnishings, and industrial uses. True flannels are made entirely or prethe process of fulling, which takes advantage of the combination of the relatively high shrinkage of wool fibers dominantly of wool and are characterized by permanent fiber disarangement on the surface of the fabric (surface cover) and permanent fiber disarrangement between the yarns in the base of the fabric (bottom cover), both of which obscure the weave or pattern arrangement of the fabric. Thus fiber disarangement is achieved through the process of fulling, which takes advantage of the combination of the relatively high shrinkage of wool fibers and the presence of epithelial scales on the surface of the wool fibers, as is well known in the textile art. For fabrics :made from fibers that do not have scales, e.g., cotton and man-made fibers, a mechanical napping action is used in an effort to obscure the weave pattern. Fabrics made in this way are sometimes called flannels, |but it is recognized in the textile industry that they are not true flannels.

It has long been desired to impart to flannel fabrics some of the properties that are characteristic of man-made fibers, notably their outstanding durability, ease-of-care properties, and resistance to attack by microorganisms and insects. The simplest approach to this objective has been to make flannels from blends of man-made fibers with wool, but such fabrics have not been entirely successful. In order to avoid interefering unduly with the felting action of the wool fibers, it has been necessary to restrict the proportion of man-made fibers in the blend to a relatively low level. This limitation has prevented taking full advantage of the beneficial characteristics of the man-made fibers. More complicated procedures have also been tried. For example, it has been proposed to pulsate the feed of spinning solution in the manufacture of man-made fibers in an effort to produce minute projections on the surface of the fibers simulating the scales of wool fibers. Also, a number of modified fabric finishing operations, chemical treatments, and the like have been proposed. Despite such atempts, widespread interest continues in production methods for fiannel fabrics made entirely of man-made fibers and possessing the desired and characteristic bottom and surface cover.

It has now been discovered that true fiannels, that is, fabrics wherein the weave pattern is totally obscured by good surface cover and good bottom cover, can be made entirely of man-made fibers by a process in which a fabric of such fibers is subjected to hot dry Schreiner calendering prior to wet-finishing operations, followed by hot fulling. By employing this process with a fabric composed of a fiber blend containing a proportion of relatively high-shrinkage bers as well as low-shrinkage fibers, a true flannel is obtained easily, economically and by use of textile skills that presently available.

Among the man-made fibers that can be used in the practice of this invention are the cellulose and cellulose derivative fibers, polyamide fibers, polyester fibers, polyacrylic and modacrylic fibers, polyolefn fibers, polyvinyl chloride fibers, polyvinyl alcohol fibers, and the like. The

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polyester and polyacrylic fibers are preferred. All such fibers are well known to the art and can be employed in the practice of the present invention without regard to their specfic chemistry or to the methods used in preparing them. While it is of the essence of the invention to provide a true fiannel from man-made fibers, small amounts of wool, cotton or the like can also be included, if desired.

The single figure of drawing is a flow chart of the basic finishing sequence utilized with the invention.

It is important to the success of the procedure that the fiber blend, whatever the chemical composition of the fibers, contain fibers of two different residual shrinkage levels. The preponderance of the fibers in the blend may have the low residual shrinkage that is characteristic of man made fibers, which is usually of the order of less than 1% to about 5%. A minimum of about 30% of the fibers in the blend, by weight, should have relatively higher shrinkage, i.e., at least about 10% and preferably from about 15 to about 25%. lFibers with even higher residual shrinkage, eg., 30-50%, may, of course, be used if available, but such high fiber shrinkage is not essential to achieve the desired flannel fabrics. Usually, no more than about 40% of high-shrinkage fibers will be required to achieve the desired fabric effect; higher proportions of high-shrinkage fibers may be used but little or no additional benefit is achieved thereby. By the term residual shrinkage is meant the linear contraction that occurs when the fibers are allowed to relax without tension in boiling water.

Blending of the fibers, spinning of yarns, and weaving of fabrics are all carried out by procedures that are standard practice in the textile industry, with two important exceptions. First, the yarns should not be twist-set, since exposure to moisture may cause shrinkage of the high-shrinkage component of` the yarns prematurely. Second, for the same reason, minimum temperatures should be used in slashing.

A typical finishing sequence that may be used with this invention is as follows: nap, crop shear, hot-dry Schreiner calender, tack, hot full, dolly wash, beck dye, apply antistat, detack, frame, nap, shear, steam, press and semi-decate. As is evident, the foregoing are conventional textile finishing operations and can readily be used by the artisan in their presently understood manner subjefctt to the significant modifications mentioned hereina er. f

The purpose of the calendering step is to compress and minutely crimp the fibers. While the applicant does not wish to be held to any particular explanation, it may be speculated that the minute crimps imparted to the fibers by the calendering operati-on operate in much the same fashion as the epithelial scales of wool to lock the fibers in a disarranged position in the course of the fiber migration induced by the subsequent fulling operation. To achieve the desired fiber deformation, several important variables in the calendering operation must be controlled. First, the temperature should be in lthe range of F. to 450 F. (38 C. to 232 C.), and preferably 100 F. to 300 F. (38 CQ to 149 0.). Pressure on the fabric should be maintained in the range of 833 lbs. per linear inch to 1666 lbs. per linear inch (149-298 kg./cm.) and preferably between 1250 land about 1666 lbs. per linear inch (223-298 kg./cm.). Rate of calender-ing depends on the temperature and pressure employed. Typically, the Ifabric is calendered twice, once on each face, at between about 20 and about 100 yds/min. (18-91meter-s per minute). An important factor in the calendering operation is the nature of the surface of the calender roll. As is well known in the textile finishing art, a Schreiner roll is a heated, hard-surfaced roll having many fine lines per inch engraved in it. Depending upon the number of lines, the roll will compress about 50% lor more of the fabric surface `du-ring calendering. Its surface may be made of alloy steel, pl-astic, ceramic or coated metal such as chromium or nickel plated steel. The surface is preferably rust-resistant. The second roll of the calender is made of a compressible composition, such as cot-ton, paper, wool, corn husk o-r other material that will present a tough, resilient, unpatterned surface to the fabric when compressed against the first roll. The engraved lines on a Schreiner roll may be parallel to the warp threads of the falbric being processed (that is, perpendicular to the axis of rotation of the roll), or at some angle thereto. In the practice of this invention, best results are achieved with a Schreiner roll having from about 200 to about 300 lines/ inch (79-118 lines/cm), oriented lat an angle of from about 20 to 40 from the warp yarns.

In the finishing of flannel fabrics made of wool, the fulling operation is normally carried out at room temperature, with the fabric sufiiciently moist and lubricated to permit migration of the wool fibers. In the practice of the present invention, the fulling operation is somewhat modified. The fabric is loaded into the fulling mill dry and conventional lubricants, such as green soap, sodium oleate or the like, are added in an amount readily determined by the skilled finisher, or the lubricant may be padded on the fabric before the fabric is placed in the fulling mill. The fulling mill is modified by the provision of a steam line for the admission of live steam. After addition of the lubricant, the fulling mill is started and steam is admitted at a rate such that maximum equili rium temperature is reached in about minutes. Fulling is continued for about 15 minutes or more after maximum equilibrium temperature is reached. This temperature will ordinarily be from about 200 F. (93 C.) to about 206 F. (97 C.) but in any event less than 212 F. 100 C.). Alternatively, the fabric may be wet out with cold water, placed in the fulling mill, lubricant added, and fulling conducted according to the method of U.S. Patent 2,972,177. By either of these mehtods or any equivalent procedure, the hot-fulling operation induces shrinkage of the high-shrinkage fibers in the blend, with the result that the fabric structure is compacted and the weave pattern obscured. As already discussed, the compacting action is assisted and preserved by the minute crimp introduced in the fibers by the hot, dry Schreiner calendering operation.

The manner of conducting the remaining finishing operations and the contributions they make to the final fabric are well known and understood.

The invention will be further illustrated by the following examples, wherein all parts are by weight unless otherwise noted.

Example l Commercially available acrylic and polyester fibers are used to make the following fiber blend:

The fibers are blended together and the blend is spun to a 17/1 cc. (34.8 tex.) yarn with a twist of 14.5 turns/in. (571 turns/meter). Part of the blend is spun to yarn with Z twist, and part of the blend is spun to yarn with S twist. The blending, spinning and weaving operations are conducted according to common practice in the industry. The yarns are woven in a 2 x 2 twill weave with a Y loom construction of 57 warp ends/in. (22.44 ends/cm.)

and 54 filling picks/in. (21.26 picks/cm). The Z-twist yarns are used for the warp and the S-twist yarns are used for the filling.

The fabric is napped and sheared. The dry fabric is then Schreiner calendered twice, once on each face. The Schreiner roll has a steel surface, engraved with 260 lines/ in. (102.36 lines/cm.) oriented at 27.5 to the warp yarns. The Schreiner roll is heated to 250 F. (121 C.). Roll pressure is 1042 lbs/linear in. (186 kg./c1r1.). The fabric is calendered at a rate of 25 yds/min. (22.86 meters/ min.

The fabric is then tacked (formed into an endless turbe), and placed dry in a fulling mill that has been modified by the :addition of a steam line. Commercially available liquid green soap is added to the extent of 12% of the dry fabric weight. The fulling mill is then closed and started in operation. At the same time, the steam valve is opened and live steam is admitted to the fulling mill at such a rate that in approximately 15 minutes van equilibrium maximum temperature of about 206 F. (97 C.) is achieved. Pulling is continued at this temperature for an additional 15 minutes.

Upon completion of fulling, the fabric is subjected to a series of conventional wet-finishing operations, namely, scouring in a dolly washer, dyeing in a beck, and application of an antistatic agent in the ybeck following dyeing. The tacking stitches are removed and the fabric is restored from the tube form to the fiat form for the final dry-finishing operations of framing to width on a tenter, napping, shearing, steaming, pressing and semi-decating.

The fabric so produced is a very desirable flannel wherein permanent disarrangement of the fibers is obtained and the weave pattern is totally obscured.

Example Il The fabric of Example I is finished according to the same procedure as in Example I except that the hot Schreiner calendering step is omitted. In the resulting fabric, the diagonal weave pattern is apparent.

Example III The fabric of Example I is finished according to the same procedure as in Example I except that the hot fulling operation is omitted. In the resulting fabric, the diagonal weave pattern is apparent.

Example IV The lfabric of Example I is finished according to the same procedure as in Example I, except that both the Schreiner calendering and the hot fulling steps are omitted. In the resulting fabric, the diagonal weave pattern is apparent. The fabric is not a true flannel.

Example V A blend is made of equal parts of the following commercially available bers:

(a) Bicomponent acrylic fiber, 3.0` denier per filament (01,33 tex/filament), two-inch (5.08 cm.) length, 4% boiloff shrinkage.

(b) Polyester fiber, 3.0 denier per filament (0.33 tex/ filament), two-inch (5.08' cm.) length, 2.5% boil-off shrinkage. The fiber blend is spun to a 15/1 cc. (39.3 tex) yarn with 13.5 tur-ns per inch (531 turns per meter) of Z twist. This yarn is `woven in a 2 x 2 twill fabric with a 64 by 5S (25.19 ends/cm. x 22.83 picks/cm.) loom construction. This fabric is finished according to the full finishing procedure of Example I and according to the variant procedures of lExamples II, III and IV. In all cases, the weave pattern remains visible 4and a true fiannel is not achieved. This example shows the importance of having a proportion of relatively high-shrinkage fibers in the fiber blend.

Example VI Commercially available fibers are used to make the following blend:

The blended fibers are spun to a l7/ l cc. (34.8 tex) yarn with 11.3 turns per inch (445 turns/meter) of Z twist. The yarn is woven `in a 2 X 2 twill weave with a 68 by 56 (26.77 ends/cm. X 22.05 `picks/tern.) loom construction. When this fabric is finished according to the complete procedure of Example I, a good, true flannel is achieved, wherein the weave pattern is totally obscured by permanent disar-rangement of fibers. The weave pattern remains apparent wlhen the fabric is finished by the procedures of Example II, III `and IV.

The foregoing examples are intended to be illustrative of the invention and not limiting. It will be seen that true annels are achieved when the essential elements of this invention are present, namely:

(a) A proportion of relatively high-shrinkage fibers in the blend, o

(b) A bot, .dry Schreiner calendering prior to any wetfinishing operation, to compress :and minutely crimp the fibers, and

(c) Hot fulling to compact the fabric structure because of shrinkage of the high-shrinkage fibers inthe blend.

It will be understood that a wide variety of fiber types, blending and spinning methods, fabric weaves and constructions and yslashing procedures, may be used. Likewise, once the essential finishing operations of Ihot-dry Schreiner calendering and hot-fulling Ihave beenaccomplished, the remaining finishing operations may be varied according to the judgment of the skilled finisher to produce the effects desired in the final fabric.

The flannel Ifabrics made according to this invention can lbe employed in the uses already known for flannel fabrics, notably n apparel fabrics, but also in home furnishings and industrial applications. Because they can be made entirely of man-made fibers, the flannel fabrics made by this invention bring to these traditional uses of flannels the additional advantages of outstanding durability, ease-of-care, vand resist-ance to attack by microorganisms and insects. Surprisingly, the fiannel fabrics made according to this invention have been found to be remarkably yfree of the pilling that has Iheretofore been generally characteristic of flannel -fabrics made at least in part of man-made fibers.

Since a wide 4scope of fiber types and manufacturing procedures may be employed in the practice of this invention -without departing from the spirit thereof, the invention is intended 4to be limited only as `defined in the appended claims.

What is claimed is:

1. A method for making flannel fabric having a weave entirely obscured by good surface and bottom cover which comprises preparing a fabric from synthetic organic fibers containing fibers having at least two different residual `shrinkage levels, about to 70I percent of the fibers present 'having a residual shrinkage below about 5 percent and the remainder of the fibers lhaving a residual shrinkage of about 10 to 50 percent, napping the fabric, calendering the resulting napped fabric to compress and minutely crimp the fibers by passing the Idry fabric, at a speed of 'at least labout 20 yards per minute, through confining rolls lat a temperature of to 450 F. and at a pressure applied by the rolls of yabout 833 to -1666 pounds per inch of roll width, and subjecting the calendered fabric to compressional working in the presence of moisture and a lubricant :at a temperature of at least 200 F. but below 212 F. to shrink the fibers, compact lche fabric structure and obscure the weave pattern; the compaction assisted and preserved by the minute crimp produced in the said calendering step.

2. A method in accordance with claim 1 in which the fibers with the higher residual shrinkage are present in an amount of 30 to 40 percent and their residual shrinkage is about 15 to 25 percent.

References Cited by the Examiner UNITED STATES PATENTS 2,828,528 4/1958 Gajjar 28--76 2,972,177 2/1961 Bid'gOOd 26-19 X 12,980,492 4/ 1961 Jamieson et al. 2,985,940 5/1961 Weldon.

ROBERT R. MACKEY, Primary Examiner. 

1. A METHOD FOR MAKING FLANNEL FABRIC HAVING A WEAVE ENTIRELY OBSCURED BY GOOD SURFACE AND BOTTOM COVER WHICH COMPRISES PREPARING A FABRIC FROM SYNTHETIC ORGANIC FIBERS CONTAINING FIBERS HAVING AT LEAST TWO DIFFERENT RESIDUAL SHRINKAGE LEVELS, ABOUT 50 TO 70 PERCENT OF THE FIBERS PRESENT HAVING A RESIDUAL SHRINKAGE BELOW ABOUT 5 PERCENT AND THE REMAINDER OF THE FIBERS HAVING A RESIDUAL SHRINKAGE OF ABOUT 10 TO 50 PERCENT, NAPPING THE FABRIC, CALENDERING THE RESULTING NAPPED FABRIC TO COMPRESS AND MINUTELY CRIMP THE FIBERS BY PASSING THE DRY FABRIC, AT A SPEED OF AT LEAST ABOUT 20 YARDS PER MINUTE, THROUGH CONFINING ROLLS AT A TEMPERATURE OF 100* TO 450*F. AND A PRESSURE APPLIED BY THE ROLLS OF ABOUT 833 TO 1666 POUNDS PER INCH OF ROLL WIDTH, AND SUBJECTING THE CALENDERED FABRIC TO COMPRESSIONAL WORKING IN THE PRESENCE OF MOISTURE AND A LUBRICANT AT A TEMPERATURE OF AT LEAST 200*F. BUT BELOW 212*F. TO SHRINK THE FIBERS, COMPACT THE FABRIC STRUCTURE AND OBSCURE THE WEAVE PATTERN; THE COMPACTION ASSISTED AND PRESERVED BY THE MINUTE CROMP PRODUCED IN THE SAID CALENDERING STEP. 